DOUGLAS M. SURGENOR 



has led to postulation of new factors. No small part of the pres- 

 ent day confusion regarding the mechanisms of blood coagula- 

 tion is due to such seemingly well-founded postulates which await 

 confirmation by study in isolated systems. 



The situation is typified by hemophilia, a hereditary de- 

 ficiency disease of historical record. The property of normal 

 plasma to compensate for this defect in clotting has been termed 

 antihemophilic globulin. However, this factor has not yet been 

 isolated free of other identifiable clotting factors, largely because 

 of its inherent fragility. As a result the precise biochemical role 

 of the antihemophilic factor still remains to be elucidated, al- 

 though it is generally believed to be utilized in the first stage of 

 coagulation, the formation of thromboplastin. The most recent 

 chapter in the study of hemophilia has made the picture more 

 complicated by forcing the division of hemophilia into at least 

 two discrete groups. This development stemmed from the ob- 

 servation of Pavlovsky (28) that the blood of certain patients 

 thought to be hemophiliacs repaired the coagulation defect of blood 

 from other hemophiliacs. Subsequent studies have established 

 that approximately one-fifth of those individuals previously 

 thought to suffer from a deficiency of antihemophilic factor were 

 in reality deficient in a new factor, which hemophiliacs possess. 

 The new factor has been purified and characterized by Aggeler 

 (1); the contrast in its properties with those ascribed to anti- 

 hemophilic factor such as its stability and its apparent failure 

 to be consumed during coagulation, bear out the clinical labora- 

 tory findings. In still another respect this new factor epitomizes 

 the confusion felt by the neophyte who delves into the coagula- 

 tion area — the new component already possesses a number of 

 pseudonyms, including plasma thromboplastin component, 

 plasma thromboplastin factor B, factor IX, and Christmas factor. 



From the standpoint of reaction kinetics, the coagulation 

 process presents several interesting features. The forward proc- 

 ess is generally considered as consisting of three reactions. The 

 first of these yields a product, thromboplastin, which is an 

 enzyme for the second reaction; this in turn yields a product, 



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